Plasma etching chamber

ABSTRACT

Disclosed is a plasma etching chamber including a gas distribution plate guiding a reaction gas to the edge of the wafer; a plate disposed to be spaced apart from the gas distribution plate; and bumper portions protruding on at least one of opposite surfaces of the gas distribution plate and the plate to allow the pressure of the reaction gas moving to the edge of the wafer to be uniform.

TECHNICAL FIELD

Disclosed herein is a plasma etching chamber, more particularly, a plasma etching chamber capable of removing a film remaining at an edge of a plasma dry-etched wafer and particles deposited around the edge of the wafer through plasma etching.

BACKGROUND ART

When fabricating a wafer, a film stacked as a pattern is typically formed throughout the entire surface of the wafer to an edge of the wafer. Here, residues produced during a dry cleaning process for plasma etching the entire top surface of the wafer are not completely removed but deposited as particles throughout the top, side and bottom surfaces of the wafer at the edge of the wafer.

If the film and particles accumulated at the edge of the wafer remain without being removed, serious damage may be caused to a semiconductor chip to be obtained.

A plasma etching chamber is used to remove the film and particles remaining at the edge of the wafer. FIG. 5 is a partial cross-sectional view of a plasma etching chamber according to a related art.

Referring to FIG. 5, the conventional plasma etching chamber includes a wafer chuck 10 on which a wafer is loaded, a ring-shaped lower electrode 11 formed along an edge of the wafer chuck 10, an upper electrode 12 disposed opposite to the lower electrode 11, and a plate 13 disposed inside the upper electrode 12.

A gas distribution plate 14 is disposed beneath the plate 13 so as to guide a reaction gas to an edge side of the wafer. A moving rod 15 is disposed on the plate 13 to allow the plate 13 ascend and descend.

In the plasma etching chamber having the aforementioned structure, when electric power is applied to the upper electrode 12, the lower electrode 11 and the wafer chuck 10, plasma is generated by a reaction gas supplied between the upper and lower electrodes 12 and 11. The generated plasma removes particles or a film stacked at the edge of the wafer.

However, the conventional plasma etching chamber has a problem that the pressure of the reaction gas at the edge of the wafer is not uniform in the process of guiding the reaction gas supplied to a space between the plate 13 and the gas distribution plate 14 to the edge of the wafer.

That is, since the pressure of the reaction gas at the edge of the wafer is different depending on positions of the edge of the wafer, the etching rate by the plasma is also different depending on the positions of the edge of the wafer, so that an amount of particles or film removed by the plasma is different depending on the positions of the wafer.

Further, the conventional etching chamber has a problem that the edge of the gas distribution plate 14 is contaminated by plasma.

DISCLOSURE Technical Problem

Therefore, in view of the above problems, provided is a plasma etching chamber capable of maintaining pressure of a reaction gas guided to an edge of a wafer to be uniform at all positions and minimizing contamination of a gas distribution plate by plasma.

Technical Solution

In accordance with an aspect, a plasma etching chamber includes a gas distribution plate guiding a reaction gas to the edge of the wafer; a plate disposed to be spaced apart from the gas distribution plate; and bumper portions protruding on at least one of opposite surface of the gas distribution plate and the plate to allow the pressure of the reaction gas moving to the edge of the wafer to be uniform.

The plasma etching chamber may further include upper and lower electrodes disposed to correspond to each other at the edge of the wafer with the wafer interposed therebetween.

The bumper portions may be alternately formed on the gas distribution plate and the plate.

The bumper portions may be formed at an edge of the gas distribution plate or the plate. The bumper portions may be formed in a ring shape.

A predetermined space may be maintained between the gas distribution plate and the plate by spacers. The spacer may have a height of 1 mm.

The bumper portion may have a height of 0.6 mm.

The gas distribution plate may further include a shield ring covering bottom and side surfaces of the edge thereof.

The width of the shield ring may be from about 15% to about 40% of the radius of the gas distribution plate.

In accordance with another aspect, a plasma etching chamber includes a gas distribution plate having a recessed groove formed at a bottom surface thereof; a baffle disposed in an inside of the recessed groove of the gas distribution plate to be spaced apart from the gas distribution plate, and guiding an inert gas supplied to the recessed groove; and bumper portions protruding on at least one of opposite surfaces of the gas distribution plate and the baffle to allow the pressure of the inert gas to be uniform.

In accordance with still another aspect, a plasma etching chamber includes a gas distribution plate guiding a reaction gas to the edge of the wafer; and a shield ring formed at an edge of the gas distribution plate to prevent contamination of the gas distribution plate. In the plasma etching chamber, the width of the shield ring may be from about 15% to about 40% of the radius of the gas distribution plate.

Yttrium may be coated on a surface of the shield ring.

Advantageous Effects

As described above, in a plasma etching chamber according to example embodiments, bumper portions are formed on a gas distribution plate or a plate, so that a film or particles deposited at an edge of a wafer can be uniformly removed. Further, the optimum width of a shield ring is maintained, so that an amount of residues coming into a space between the gas distribution plate and the shield ring can be reduced, and replacement cost of the gas distribution plate can be saved by decreasing contamination of the gas distribution plate.

DESCRIPTION OF DRAWINGS

FIG. 1 is a partial cross-sectional view of a plasma etching chamber.

FIG. 2 is a partial cross-sectional view of the plasma etching chamber after a moving rod descends.

FIG. 3 is a partial enlarged view of portion A of FIG. 1.

FIG. 4 is a schematic plan view of a gas distribution plate.

FIG. 5 is a partial cross-sectional view of a plasma etching chamber according to a related art.

MODE FOR INVENTION

Hereinafter, a plasma etching chamber will be described in detail with reference to the accompanying drawings.

FIG. 1 is a partial cross-sectional view of a plasma etching chamber. FIG. 2 is a partial cross-sectional view of a plasma etching chamber after a moving rod descends. FIG. 3 is a partial enlarged view of a portion A of FIG. 1. FIG. 4 is a schematic plan view of a gas distribution plate.

Referring to FIGS. 1 and 2, the plasma etching chamber 100 includes a chamber wall 20 providing a space isolated from the outside thereof, a moving rod 21 operated by an actuator (not shown) while passing through an upper portion of the chamber wall 20, and a plate formed beneath the moving rod 21. The plate includes an upper plate 22 and a lower plate 23.

The lower plate 23 is disposed beneath a bottom surface of the upper plate 22, and a ring-shaped upper electrode 24 is disposed along an edge of the lower plate 23. The upper electrode 24 is fixed to the upper plate 22 by a first bolt 241.

A gas distribution plate 25 is disposed beneath the upper and lower plates 22 and 23 while being spaced apart from the upper and lower plates 22 and 23 with a predetermined spacing. The gas distribution plate 25 guides a reaction gas to an edge of a wafer. Here, the reaction gas is supplied to the space between the lower plate 23 and the gas distribution plate 25. The gas distribution plate 25 may be made of an insulating material such as alumina oxide (Al₂O₃).

Meanwhile, the lower plate 23 may be provided optionally. When the lower plate 23 is not provided, the gas distribution plate 25 may be fixed directly to the upper plate 22. When the upper plate 22 is protruded downwardly by the thickness of the lower plate 23, the gas distribution plate 25 may be fixed to a protruding portion of the upper plate 22. For example, when the lower plate 23 is not provided, the upper plate 22 may be protruded downwardly by the thickness of the removed lower plate 23, or may not be protruded.

A recessed groove 251 is formed at the center of a bottom surface of the gas distribution plate 25, and a baffle 26 is disposed in an inside of the recessed groove 251. The baffle 26 allows an inert gas (e.g., nitrogen gas) supplied to the center of the wafer to be distributed. The baffle 26 may be provided optionally.

A shield ring 27 is formed at the bottom and side surfaces of an edge of the gas distribution plate 25 so as to adsorb residues such as polymer, which may be produced when the wafer is etched. The shield ring 27 is fixed to the gas distribution plate 25 by a second bolt 252, and may be formed to have a dielectric constant different from that of the gas distribution plate 25. For example, the shield ring 27 may be made of sintered yttrium having a dielectric constant of 11, and the gas distribution plate 25 may be made of alumina oxide having a dielectric constant of 8.4. The difference of dielectric constants results in decrease of the accumulation of electric charges by plasma discharge at an unnecessary portion.

The width L1 of the shield ring 27 may be set to be from about 15% to about 40% of the radius L2 of the gas distribution plate 25. If the width L1 of the shield ring is smaller than 15%, the shield ring 27 may not cover the gas distribution plate 25 when high-density plasma is formed, and etching residues may come into a space between the gas distribution plate 25 and the shield ring 27. If the width L1 of the shield ring 27 exceeds 40%, the shield ring 27 may cover an unnecessary portion of gas distribution plate 25, and manufacturing cost may be increased.

For example, the radius L2 of the gas distribution plate 25 may be from about 290 mm to about 300 mm, and the width L1 of the shield ring 27 may be from about 45 mm to about 116 mm.

Yttrium may be coated on surfaces of the gas distribution plate 25 and the shield ring 27. Yttrium has excellent polymer adsorption property and superior chemical resistance. Therefore, yttrium allows particles to be adsorbed and removed without chemical modification during a cleaning process.

A ring-shaped lower electrode 28 is disposed below the upper electrode 24 while being spaced apart from the upper plate 24 at a predetermined space. A wafer chuck 32 is disposed inside the lower electrode 28 with an insulating ring 30 interposed between the wafer chuck 32 and the lower electrode 28. The wafer chuck 32 is electrically connected to a typical plasma oscillator (not shown) to receive a high frequency applied from the plasma oscillator while vacuum adsorbing a wafer loaded on the top surface of the wafer chuck 32.

The external diameter of the upper electrode 24 may be identical to that of the lower electrode 28. Accordingly, the shape of the generated plasma may be completely symmetrical, so that it is possible to be operated as a low-capacity plasma oscillator.

The wafer chuck 32 is perfectly insulated from the lower electrode 28 through an insulating layer 34 disposed below the wafer chuck 32.

Referring FIG. 3, the plasma etching chamber 100 includes bumper portions 36 disposed in the space between the lower plate 23 and the gas distribution plate 25, through which the reaction gas is supplied. The bumper portion 36 is formed to protrude with a height H smaller than that of the spacing between the lower plate 23 and the gas distribution plate 25. For example, the spacing between the gas distribution plate 25 and the lower plate 23 may be 1 mm, and the height of the bumper portion 36 may be 0.6 mm.

The bumper portions 36 allow the pressure of the reaction gas at the edge of the wafer to be uniform by blocking the flow of the reaction gas. The bumper portions 36 may be alternately formed on the lower plate 23 and the gas distribution plate 25 along the progress direction of the reaction gas (see the curved arrow in FIG. 3). This is to lengthen the flow path of the reaction gas, thereby extending the time during which the reaction gas remains in the space between the lower plate 23 and the gas distribution plate 25. The number of bumper portions 36 may be varied depending on the pressure of the reaction gas.

As shown in FIG. 4, the bumper portion 36 may be formed at the edge of the gas distribution plate 25 so as to protrude in a ring shape. A plurality of spacers 37 providing the space between the gas distribution plate 25 and the lower plate 25 may be formed on a top surface of the gas distribution plate 25 at a predetermined distance. At this time, the bumper portion 36 is formed to have a height smaller than that of the spacer 37. Although the bumper portion 36 may be formed in a ring shape, the shape is not limited thereto. That is, the bumper portion 36 may be formed with various shapes, including, e.g. a rectangular shape.

The operation of the plasma etching chamber 100 having the aforementioned configuration will be described. An inert gas supplied through the gas distribution plate 25 is distributed by the baffle 26 sp that a non-discharge region is formed at an inside of a wafer. Simultaneously, a reaction gas supplied to the lower plate 23 and the gas distribution plate 25 moves to an edge of the wafer and then generates plasma by means of voltages respectively applied to the upper and lower electrodes 24 and 28. The generated plasma etches particles deposited on a portion formed from top to bottom surfaces of the edge of the wafer.

In the aforementioned process, the bumper portions 36 blocks the flow of the reaction gas so that the pressure of the reaction gas at the edge of the wafer is maintained uniform at all positions, thereby generating uniform plasma. Accordingly, an etching rate of particles becomes identical for all positions. Further, because the optimum width of the shield ring 27 is maintained, contamination of the gas distribution plate caused by the plasma may be effectively prevented.

As described above, the bumper portions 36 are formed on the gas distribution plate 25 and the lower plate 23 so as to allow the pressure of the reaction gas to be uniform. In the same manner described above, the aforementioned bumper portions may be formed on at least one of opposite surfaces of the recessed groove 251 and the baffle 26 so as to allow the pressure of the inert gas supplied to the recessed groove 251 to be uniform.

The plasma etching chamber has been described in detail with reference to example embodiments. However, it will be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the accompanying claims and their equivalents.

INDUSTRIAL APPLICABILITY

In a plasma etching chamber, a film or particles deposited at an edge of a wafer can be uniformly removed, and replacement cost of a gas distribution plate can be saved by decreasing contamination of the gas distribution plate. 

1. A plasma etching chamber for etching an edge of a wafer, comprising: a gas distribution plate guiding a reaction gas to the edge of the wafer; a plate disposed to be spaced apart from the gas distribution plate; and bumper portions protruding on at least one of opposite surfaces of the gas distribution plate and the plate.
 2. The plasma etching chamber as set forth in claim 1, further comprising upper and lower electrodes disposed to correspond to each other at the edge of the wafer with the wafer interposed therebetween.
 3. The plasma etching chamber as set forth in claim 1, wherein the bumper portions are alternately formed on the gas distribution plate and the plate.
 4. The plasma etching chamber as set forth in claim 1, wherein the bumper portions are formed at an edge of the gas distribution plate or the plate.
 5. The plasma etching chamber as set forth in claim 1, wherein the bumper portions are formed in a ring shape.
 6. The plasma etching chamber as set forth in claim 1, wherein a predetermined spacing between the gas distribution plate and the plate is maintained by spacers.
 7. The plasma etching chamber as set forth in claim 6, wherein the spacing is 1 mm.
 8. The plasma etching chamber as set forth in claim 7, wherein the bumper portion has a height of 0.6 mm.
 9. The plasma etching chamber as set forth in claim 1, wherein the gas distribution plate further comprises a shield ring covering bottom and side surfaces of the edge thereof.
 10. The plasma etching chamber as set forth in claim 9, wherein the width of the shield ring is from about 15% to about 40% of the radius of the gas distribution plate.
 11. A plasma etching chamber etching an edge of a wafer, comprising: a gas distribution plate having a recessed groove formed at a bottom surface thereof; a baffle disposed in an inside of the recessed groove of the gas distribution plate to be spaced apart from the gas distribution plate, the baffle guiding an inert gas supplied to the recessed groove; and bumper portions protruding on at least one of opposite surfaces of the gas distribution plate and the baffle.
 12. A plasma etching chamber for etching an edge of a wafer, comprising: a gas distribution plate guiding a reaction gas to the edge of the wafer; and a shield ring formed at an edge of the gas distribution plate so as to prevent contamination of the gas distribution plate, wherein the width of the shield ring is from about 15% to about 40% of the radius of the gas distribution plate.
 13. The plasma etching chamber as set forth in claim 12, wherein yttrium is coated on a surface of the shield ring.
 14. The plasma etching chamber as set forth in claim 2 wherein the bumper portions are formed at an edge of the gas distribution plate or the plate.
 15. The plasma etching chamber as set forth in claim 2 wherein its gas distribution plate further comprises a shield ring covering bottom and side surfaces of the edge thereof. 